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Mysql SQL多表查询,联接语法_Mysql_Sql_Syntax - Fatal编程技术网

Mysql SQL多表查询,联接语法

Mysql SQL多表查询,联接语法,mysql,sql,syntax,Mysql,Sql,Syntax,我有以下建议: 表字段名称 活动的activeID,activeName 活动类别活动ID,类别ID CategoriescategoryID,categoryName from Active a left join (select b.activeID activeID, c.categoryName CategoryName from ActiveCategories b left join Categories c on b

我有以下建议: 表字段名称

活动的activeID,activeName

活动类别活动ID,类别ID

CategoriescategoryID,categoryName

from Active a 
    left join (select b.activeID activeID, c.categoryName CategoryName
            from ActiveCategories b
                left join Categories c on b.categoryID = c.categoryID) d
        on a.activeID = d.activeID
我希望查询,以便结果获取ActiveCategories上活动的左连接,但它应该显示相应的categoryName[来自Categories],而不是CategoryID[来自ActiveCategories]整数。 到目前为止,我已成功显示整数,但没有显示相应的名称。

请尝试:

选择a.activeID、a.activeName、d.categoryName

from Active a 
    left join (select b.activeID activeID, c.categoryName CategoryName
            from ActiveCategories b
                left join Categories c on b.categoryID = c.categoryID) d
        on a.activeID = d.activeID

您可以向我们展示您尝试过的任何内容吗?您只需要添加另一个与Categories表的联接。为什么这对您不起作用?我的尝试>>>sql=SELECT Active.*,ActiveCategories.CategoryID从Active左侧加入Active上的ActiveCategories.ActiveID=ActiveCategories.ActiveID[ActiveID]您可能希望coalescc.categoryName,'Unknown'作为categoryName